Light emission device

ABSTRACT

A light emission device, including at least two LED dies having differing spectral output from one another; and phosphor material including one or more phosphors, arranged to receive spectral output from at least one of the LED dies and to responsively emit a phosphor output, as a component of a spectral output of the light emission device. In a specific arrangement, the multiple LED dies and phosphor material are arranged to produce a white light output having a color temperature selected from among (i) color temperature in a range of from 1350° K to 1550° K, (ii) color temperature in a range of from 2400° K to 3550° K and (iii) color temperature in a range of from 4950° K to 6050° K.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to light emission devices incorporatinglight emitting diode (LED) and phosphor components.

2. Description of the Related Art

In the illumination art, a variety of approaches have been employed toproduce light of desired spectral character.

LEDs have come into widespread usage as a result of their advantages,which include small size, long life, low energy consumption, and lowheat generation.

U.S. Pat. No. 6,513,949 issued Feb. 4, 2003 describes a hybrid lightingsystem for producing white light, including at least one LED and aphosphor-LED, in which the color and number of the LEDs and/or thephosphor of the phosphor-LED may be varied.

U.S. Pat. No. 6,600,175 issued Jul. 29, 2004 describes a light emittingassembly including an LED emitting a first, relatively shorterwavelength radiation, and a down-converting luminophoric medium, e.g.,phosphoric medium, that in exposure to such first radiation,responsively emits a second, relatively longer wavelength radiation.

White LED devices have been commercialized that utilize a blue LED and aYAG phosphor (Y₃Al₅O₁₂ doped with cerium) that partially absorbs blueradiation (centered on 470-480 nm) from the blue LED and emits lighthaving a broad wavelength range with a dominant yellow characteristic(centered on ˜550-600 nm).

The commercially available LED/phosphor devices for production of whitelight do not provide high conversion efficiency color rendering invarious spectral regimes of interest. For example, in many applications,consumers prefer white light having color (as quantifiable by colortemperature and color rendering index values) that matches sunlight,conventional incandescent bulb light, or fire light such as candlelight.

There is accordingly a continuing need in the art for efficientLED/phosphor illumination systems producing light having a colorrendering that closely matches a predetermined spectral distribution.

SUMMARY OF THE INVENTION

The present invention relates to light emission devices incorporatinglight emitting diode (LED) and phosphor components.

In one aspect, the invention relates to a light emission deviceincluding: at least two LED dies having differing spectral output fromone another; and phosphor material including one or more phosphors,arranged to receive spectral output from at least one of the LED diesand to responsively emit a phosphor output as at least part of spectraloutput of the light emission device.

In another aspect, the invention relates to a method of generatinglight, including exciting at least two LED dies having differingspectral output from one another, to emit spectral outputs from each ofsuch dies, and impinging the spectral output from at least one of suchdies on phosphor material including one or more phosphors, toresponsively emit a phosphor output as at least part of spectral outputconstituting such light.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional elevation view of a light emission deviceaccording to one embodiment of the invention.

FIG. 2 is a graph of intensity as a function of wavelength, for each ofthe LED die elements and phosphors employed in the light emission deviceof FIG. 1, as isolated components.

FIG. 3 is a graph of intensity as a function of wavelength, for theintegrated output of the light emission device of FIG. 1.

FIG. 4 is an LED multiple die array including five different LED diecolors (shown as Blue LED, Aqua LED, Green LED, Yellow LED and Red LED).

FIG. 5 is a graph of intensity as a function of wavelength, for each ofthe LED die elements employed in the FIG. 5 LED array, as isolatedcomponents.

FIG. 6 is a graph of intensity as a function of wavelength, as theintegrated output of the LED array of FIG. 4.

FIG. 7 is a simplified schematic depiction of a light emission deviceaccording to another embodiment of the invention, incorporating an LEDmultiple die array including five different LED die colors (shown asBlue LED, Aqua LED, Green LED, Yellow LED and Red LED) and a phosphormixture overlying the multiple die array.

FIG. 8 is a graph of intensity as a function of wavelength, for each ofthe LED die elements and phosphor species employed in the FIG. 7 lightemission device, as isolated components.

FIG. 9 is a graph of intensity as a function of wavelength, as theintegrated output of the light emission device of FIG. 7.

FIG. 10 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for a lightemission device according to one embodiment of the invention, includingtwo visible light LEDs (green and blue) and two phosphors.

FIG. 11 shows the spectral distribution arising from a combination of a470 nm LED, a 527 nm LED, a CaGa₂S₄:Eu²⁺ phosphor and a ZnGa₂S₄:Mn²⁺phosphor.

FIG. 12 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for a lightemission device according to another embodiment of the invention,including two visible light LEDs (blue and red) and two phosphorsexcited only by the blue LED.

FIG. 13 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for a lightemission device according to still another embodiment of the invention,including two LEDs (ultraviolet and blue) and one phosphor.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

The present invention relates to light emission devices incorporatinglight emitting diode (LED) and phosphor components.

Light emission devices of the invention enable excellent color renderingto be achieved by the provision of at least two LED dies havingdiffering spectral character from one another, and a phosphor materialincluding one or more phosphors. The phosphor material is arranged toreceive energy from at least one of the multiple LED dies and toresponsively emit a phosphor output, as at least part of spectral outputof the light emission device. The light emission device has a spectraloutput that differs from the spectral character of each of the LED dies,and that differs from the phosphor output.

By integrating the emissions of the multiple LED dies and the phosphormaterial containing at least one phosphor component, the light emissiondevice of the invention may be constituted to achieve a superior colorrendering that matches predetermined spectral distributions of light,e.g., sunlight, candle light (or other fire), or light produced byincandescent bulbs.

By way of specific example, the light emission device of the inventionmay be fabricated to provide a white light output having a colortemperature in one of the following white light color temperatureregimes (A), (B) and (C):

(A) white light having a color temperature in a range of from 1350° K to1550° K;

(B) white light having a color temperature in a range of from 2400° K to3550° K;

(C) white light having a color temperature in a range of from 4950° K to6050° K.

As further specific examples, the color temperature of candles is ˜1500°K, the color temperature of incandescent bulbs is ˜2680-3000° K, thecolor temperature of sunrise and sunset is ˜3200° K, and the colortemperature of a sunny day at noon is ˜5500°K. By appropriate selectionof LED die components and phosphor species, a close approach to thecolor temperature of interest can be achieved in the light output of thelight emission device.

In various specific embodiments of the invention, such as thoseillustratively mentioned above, the spectral output of the lightemission device can be white light. In other embodiments, the spectraloutput of the light emission device can be light having a specific colorother than white light. In still further embodiments, the spectraloutput of the light emission device may include output that is outsidethe visible light spectrum.

The invention achieves superior color rendering at good conversionefficiency, and provides degrees of freedom in light emission devicedesign that permit optimal spectral outputs to be achieved, e.g., of aspecific spectral profile, or of a spectral character that is resistantto color change over the service life of the device. In the latterrespect, it is known that phosphors and LEDs tend to age, leading tocolor changes over time. The light emission device of the invention, byvirtue of its multiple LED die components and one or more phosphorcomponents, may be fabricated and arranged to compensate for aging ofLEDs and/or phosphors.

It is contemplated by the invention to utilize a predeterminedcombination of LED(s) and phosphor(s) that are matched to one another intheir aging profiles so that there is a consistent aging of the overalldevice during its service life, so that the color of the output light ismaintained over the entire service life, albeit possibly changing inintensity as the device ages. In this respect, it is pointed out thatthe lifetimes of LEDs are typically measured in the tens of thousands ofhours, and that the change in output over such period of time may berelatively small as regards the LEDs of the device.

More generally, the invention contemplates the combination of LEDs andphosphors that are selectively matched in the device including same, toachieve a predetermined character of output emission.

It also is contemplated by the invention, in another embodiment thereof,to use a combination of LEDs and phosphors that are matched in the lightemission device, to provide a change of color at a predetermined pointin the service life of the device. For such purpose, the change of colormay be relatively rapid in transition, e.g., to prompt an action on thepart of a user or a service technician, such as change-out of theillumination device, or change-out of a battery or other power supplymeans for such device, or other maintenance or service or other actionthat is desirably carried out after a period of operation and that isindicatable by a prompting color change.

Although the invention is discussed primarily herein in reference to thegeneration of a visible illumination output, i.e., in a visibleillumination spectrum, the invention nonetheless also is broadlyapplicable to the generation of emission outputs in non-visible spectralregions, e.g., in an IR spectrum, UV spectrum or other non-visiblespectrum.

The light emission device of the invention differs from priorLED-phosphor devices, in the provision of multiple differing LED dies,each associated with the phosphor material in the device.

The phosphor material can contain one or more than one phosphor species,as desired in a specific end use application of the invention.

The phosphor material is stimulated by radiation from LED die element(s)of the light emission device, so as to produce a phosphor output ofparticular spectral character. The spectral output of the overall devicetherefore will be a composite radiation that will be “smoothed” orotherwise blended, in relation to a corresponding device with only asingle LED die. Individual phosphor species can be selected to absorball or substantially all of the radiation emitted by a given LED die, oralternatively to absorb only a portion of the incident radiation thereonderived from the LED die while allowing the remainder of the emissionfrom the LED die to transmit unabsorbed from the light emission device.

In one embodiment, the light emission device is provided as a unitaryarticle including the multiple LED dies and phosphor(s) in a protectivepackage, in which the multiple dies are arranged in an array overlaid bythe phosphor material. The multiple LED dies can for example bepositioned on one or more reflector cups or other support structure,with the phosphor material overlying the dies being provided as a layerof the phosphor material. The phosphor material when including multiplephosphor species can be constituted as a uniform, e.g., substantiallyhomogeneous, mixture of the respective phosphors.

It is contemplated by the invention to shape the phosphor(s) in anoverlying coating or mass on the LED(s) so as to match the thickness ofthe phosphor to the primary emission of the LED(s), so that the primaryemission radiation traverses a generally same thickness of the phosphorcoating or mass, over the entire periphery or output surfaces of theLED(s), to thereby provide better uniformity of spectral output from theillumination device. The invention also contemplates the shaping of theLED die to provide a directionally enhanced emission of primaryradiation, or a more uniform emission of primary radiation than isotherwise achievable in the absence of such LED die shaping. In variousembodiments of the invention, therefore, it may be desirable toconformally coat phosphor material(s) on the LED die(s) to achieve apredetermined advantageous character of the light emission device.

The phosphor material may be applied over the multiple dies in anysuitable manner, e.g., in a curable liquid formulation that is potted,dip-coated, brushed, rolled, sprayed or otherwise applied over themultiple dies, e.g., to form a layer of the phosphor material in whichthe phosphor component(s) are homogeneously dispersed in the layer.

It may be desirable in specific applications to place the LED dies inrespective individual reflector cups and to mount the cups in a single“bulb” or package. Alternatively, it may be desirable to dispose all LEDdies inside a single reflector package. Multiple phosphors may be spreadover multiple LED dies or a select phosphor may be spread over aspecific LED die. Individual LED die/phosphor packaging may be employed,with each LED die being arranged to impinge emitted energy on a phosphorto produce an integrated output light from the device.

To control the amount of light emitted by the LED dies, current can besourced individually to each of the dies, if the associated cost andcomplexity of wiring and power supply arrangements is suitable for theintended end use application. Alternatively, light output of the lightemission device can be controlled by variation in die fabrication, dienumber, die shape, die size (area), contact quality, overall structureresistance, or the like, or other aspects of the LED design.

The phosphor material can be of any suitable type, including forexample, YAG (yttrium aluminum garnet) phosphor, CaGa₂S₄:Eu²⁺ phosphor,ZnGa₂S₄:Mn²⁺ phosphor, SrSCu+,Na phosphor, CaSO₄:Bi phosphor or anyother suitable type of phosphor material.

The phosphor material may include components other than the phosphor(s)per se, such as a carrier medium in which the phosphor(s) are dispersed.In one embodiment, the carrier medium includes a glass or a polymericcomposition that is suitably transmissive of emitted energy, e.g., fromthe LED die and/or phosphor components, to provide the desired characterof light output from the light emission device. Polymeric compositionsuseful for such purpose may be of any appropriate type, including,without limitation, compositions containing polyolefin, polyimide,polysulfone, polyacrylate, polymethacrylate, polycarbonate, orcorresponding copolymers.

The phosphor(s) may be dispersed in the carrier medium in a particulateor other discontinuous form, in an amount ensuring a desired characterand extent of conversion of LED die-emitted energy to light output fromthe phosphor(s) in the carrier medium.

The provision of multiple differing LED dies in a unitary packaging withthe phosphor material affords a compact and efficient structure capableof producing a high intensity light output of a desired spectralcharacter. By appropriate selection of the different LED dies andphosphor(s) for the light emission device, the radiative emissions ofthe respective dies and phosphor(s) can be integrated in a mannerachieving close matches to predetermined illumination spectra, such as aspectrum of sunlight, candle light or light emitted by a conventionalincandescent filament light bulb.

The selection of LED dies and phosphor(s) thus can be made in a mannerthat results in small energy differences between the LED dies, asilluminating sources, and phosphor(s) emissively responding toimpingement of energy from such dies, so that highly efficient lightproduction is achieved.

The invention will now be described in relation to the drawings, inwhich FIG. 1 is a sectional elevation view of a light emission device 10according to one embodiment of the invention. The device 10 is shown ina simplified schematic form for clarity of description and illustration,without depiction of additional light extracting optics, e.g.,reflecting surfaces, or focusing lens(es), and without depiction ofwiring, package leads, bond structures, power supplies or the like.

The light emitting device 10 includes a reflector cup 12 or similarsupport structure, on which is mounted an LED die 14 of a first colorand an LED die 16 of a second color. In a specific arrangement of suchmulti-die array, the first LED die 14 is a blue LED die and the secondLED die 16 is a green LED die.

The multi-die array is covered with a phosphor material 18, which in aspecific embodiment may include a mixture of two phosphors dispersed ina polymeric matrix such as polycarbonate. The phosphors in the phosphormaterial 18 are appropriately selected to be excited by radiationemitted from the multi-die array and to responsively emit outputradiation, so that the integrated output of the light emission device,deriving from the multi-die array and phosphor material, is of a desiredspectral character.

FIG. 2 is a graph of intensity as a function of wavelength, for each ofthe LED die elements and phosphor species employed in the light emissiondevice of FIG. 1, as isolated components. The graph shows the spectralintensity of emissions of the first LED die (“Blue LED”), second LED die(“Green LED”), first phosphor (“Phosphor 1”) and second phosphor(“Phosphor 2”), when each of such components is considered individually.

FIG. 3 is a graph of intensity as a function of wavelength, for theintegrated output (“Integrated Output 1”) of the light emission deviceof FIG. 1, as including the LED dies and phosphor components whosespectra are shown in FIG. 2. Such integrated output provides a spectraldistribution that approximates the spectral distribution of candlelight.

FIG. 4 is an LED multiple die array 22 including five different LED diecolors. The dies A, B, C, D and E (labeled as “Blue LED,” “Aqua LED,”“Green LED,” “Yellow LED” and “Red LED,” respectively) constitute themultiple die array.

FIG. 5 is a graph of intensity as a function of wavelength, for each ofthe LED dies employed in the FIG. 5 LED die array, as isolatedcomponents. The graph shows the spectral intensity of emissions of thefirst LED die (“Blue LED”), second LED die, (“Aqua LED”), third LED die(“Green LED”), fourth LED die (“Yellow LED”) and fifth LED die (“RedLED”), when each of such die components is considered individually.

FIG. 6 is a graph of intensity as a function of wavelength, as the whitelight integrated output (“Integrated Output 2”) of the LED die array ofFIG. 4. The integrated light consists of five discrete colors, but thereare gaps in the spectral distribution as compared to the spectrumproduced by a conventional incandescent filament light bulb.

FIG. 7 is a simplified schematic depiction of a light emission deviceaccording to another embodiment of the invention, incorporating an LEDmultiple die array 22 including five different LED dies A, B, C, D and E(labeled as “Blue LED,” “Aqua LED,” “Green LED,” “Yellow LED” and “RedLED,” respectively), as disposed on a support surface 26 and a phosphormixture 24 overlying the multiple die array.

FIG. 8 is a graph of intensity as a function of wavelength, for each ofthe LED die elements and phosphor species employed in the FIG. 7 lightemission device, as isolated components. The graph shows the spectralintensity of emissions of the first LED die A (“Blue LED”), the secondLED die B (“Aqua LED”), the third LED die C (“Green LED”), the fourthLED die D (“Yellow LED”) and the fifth LED die E (“Red LED”), as well asthe distributions associated with the phosphor material in phosphormixture 24, when each of such LED die and phosphor components isconsidered individually.

FIG. 9 is a graph of intensity as a function of wavelength, as theintegrated output of the light emission device of FIG. 7. By comparisonof the spectral distributions of FIG. 6 and FIG. 9, it is seen that theutilization of the phosphor mixture 24 in the device yields a moresmoothly varying spectral distribution that is correspondingly a betterspectral match to the desired incandescent bulb spectrum, than thecorresponding LED die array lacking the phosphor mixture 24.

The features and advantages of the invention are more fully shown by thefollowing non-limiting examples, as illustrative of specific aspects,features and embodiments of the invention.

EXAMPLE 1 Light Emission Device Including Two Visible Light LEDs and TwoPhosphors

To encompass the desired spectral range, two LEDs, an X-Brite deep blue(460 nm) LED and an X-Brite green (527 nm) LED, both commerciallyavailable from Kingbright Corporation, Tapei, Taiwan, are utilized tofabricate a light emission device of the type shown in FIG. 2. The LEDsfunction as light sources and excite a phosphor mixture including twophosphors. The first phosphor in the phosphor mixture is a CaGa₂S₄:Eu²⁺phosphor, which emits a yellowish-green light and which is excited withlight having a wavelength shorter than ˜480 nm (˜25% absorption). Thesecond phosphor in the phosphor mixture is a ZnGa₂S₄:Mn²⁺ phosphor,which emits an orange-red light and which is excited by light having awavelength shorter than about 510 nm (˜50% absorption). The die size ofeach of the two LED dies, and the concentration of each of the twophosphors in the phosphor mixture, are adjusted to achieve a spectralresponse similar to natural daylight at noon.

FIG. 10 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for such lightemission device, including two visible light LEDs (green and blue) andtwo phosphors. In FIG. 10, the bars C, D, E and F show the spectralregion covered by the emission from the device, and bars A and B showthe excitation range for the device.

FIG. 11 shows the spectral distribution arising from the combination ofthe 470 nm LED, the 527 nm LED, the CaGa₂S₄:Eu²⁺ phosphor and theZnGa₂S₄:Mn²⁺ phosphor. The LED emission intensity and the phosphorconcentrations have been adjusted to yield the spectral distributionshown in the graph.

EXAMPLE 2 Blue and Red LEDs with Two Phosphors Excited Only by the Blue

To encompass the desired spectral range, two LEDs, an X-Brite deep blue(460 nm) LED and an X-Brite red (670 nm) LED, both commerciallyavailable from Kingbright Corporation, Tapei, Taiwan, are utilized tofabricate a light emission device of the type shown in FIG. 2. The LEDsfunction as light sources and the blue is used to excite a phosphormixture including two phosphors. The first phosphor in the phosphormixture is a SrSCu+,Na phosphor, which emits a green light centered on530 nm and which is excited with light shorter than ˜490 nm (˜20%absorption). The second phosphor in the phosphor mixture is a CaSO₄:Biphosphor, which emits a yellow orange light and which is excited bylight shorter than about 510 nm (˜10% absorption). The LED dies arecoated by the phosphors during manufacture, with all dies being mountedin a single package to facilitate fabrication and assembly. Thephosphors are excited by the blue light emitted from the blue LED die,but simply transmit the red light emitted by the red LED die. The diesize of each of the two LED dies, and the concentration of each of thetwo phosphors in the phosphor mixture, are adjusted to achieve aspectral response similar to natural daylight at noon.

FIG. 12 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for the lightemission device including the two visible light LEDs (blue and red) andthe mixture of two phosphors excited only by the blue LED die emission.In FIG. 11, the bars C, D, E and F show the spectral region covered bythe emission from the device, and bars A and B show the excitation rangefor the device.

EXAMPLE 3 Ultraviolet and Blue LEDs and One Phosphor

To encompass the desired spectral range approaching a solar spectrum,two LEDs, a MegaBrite ultraviolet (460 nm) LED, commercially availablefrom Cree, Inc., Durham, N.C., USA, and an X-Brite signal green (505 nm)LED, commercially available from Kingbright Corporation, Taipei, Taiwan,are employed to fabricate a light emission device of the general typeshown in FIG. 2, in which the phosphor material contains only onephosphor. The ultraviolet LED acts to excite the phosphor while thegreen LED contributes to the emission to ensure that the spectraldistribution produced by the light emission device closely matches thedesired solar spectrum. The phosphor employed in the device is aCaMgSi₂O₆:Eu²⁺,Mn²⁺ phosphor, which emits in the blue, yellow-green,orange and red. This phosphor is transmissive to green and the X-Britesignal green LED produces light in this spectral region. The phosphor isexcited by light shorter than 410 nm (˜50% absorption). The die size ofeach of the two LED dies, and the concentration of the phosphor, areadjusted to achieve a spectral response similar to natural daylight atnoon.

FIG. 13 is a graphical depiction showing wavelength, in nm, and energy,in electron volts, and associated bars showing visible light spectrum,excitation range and spectral region spanned by emission, for such lightemission device incorporating two LEDs (ultraviolet and blue) and oneCaMgSi₂O₆:Eu²⁺,Mn²⁺ phosphor. In FIG. 12, the bars B, C, D and E showthe spectral region covered by the emission from the device, and bar Ashows the excitation range for the device.

While the invention has been described herein with reference to specificaspects, features and embodiments, it will be recognized that theinvention is not thus limited, but rather extends to and encompassesother variations, modifications and alternative embodiments.Accordingly, the invention is intended to be broadly interpreted andconstrued to encompass all such other variations, modifications, andalternative embodiments, as being within the scope and spirit of theinvention as hereinafter claimed.

1. A light emission device, comprising: at least two LED dies havingdiffering spectral output from one another; and phosphor materialincluding one or more phosphors, arranged to receive spectral outputfrom at least one of the LED dies and to responsively emit a phosphoroutput as at least part of spectral output of the light emission device.2. The light emission device of claim 1, wherein the phosphor materialis arranged to receive spectral output from at least two LED dies. 3.The light emission device of claim 1, wherein the phosphor material isarranged to receive spectral output from all of the at least two LEDdies.
 4. The light emission device of claim 1, wherein the phosphormaterial includes at least two phosphors.
 5. The light emission deviceof claim 1, including two LED dies.
 6. The light emission device ofclaim 5, wherein the phosphor material includes two phosphors.
 7. Thelight emission device of claim 1, including five LED dies.
 8. The lightemission device of claim 1, wherein the spectral output of the lightemission device is a white light spectral output.
 9. The light emissiondevice of claim 1, wherein the spectral output of the light emissiondevice is light other than white light.
 10. The light emission device ofclaim 1, wherein the spectral output of the light emission devicesubstantially matches an illumination spectrum of sunlight, candlelight, or incandescent filament light.
 11. The light emission device ofclaim 1, wherein the spectral output of the light emission devicesubstantially matches an illumination spectrum of fire.
 12. The lightemission device of claim 1, wherein the spectral output of the lightemission device is white light having a color temperature in one of thefollowing white light color temperature regimes (A), (B) and (C): (A)white light having a color temperature in a range of from 1350°K to1550° K; (B) white light having a color temperature in a range of from2400°K to 3550° K; (C) white light having a color temperature in a rangeof from 4950° K to 6050° K.
 13. The light emission device of claim 12,wherein the white light comprises light having a color temperature inwhite light color regime (A).
 14. The light emission device of claim 12,wherein the white light comprises light having a color temperature inwhite light color regime (B).
 15. The light emission device of claim 12,wherein the white light comprises light having a color temperature inwhite light color regime (C).
 16. The light emission device of claim 1,wherein the at least two LED dies and phosphor material are disposed ina unitary package.
 17. The light emission device of claim 1, wherein theat least two LED dies are overlaid by the phosphor material.
 18. Thelight emission device of claim 1, wherein the phosphor material iscoated on the LED dies.
 19. The light emission device of claim 1,wherein the phosphor material is conformally coated on the LED dies. 20.The light emission device of claim 1, wherein the phosphor material iscoated on the LED dies, so that spectral output of the LED diestraverses a substantially constant thickness of the phosphor materialover the LED dies.
 21. The light emission device of claim 1, wherein thephosphor material is dispersed in a glass or polymeric composition. 22.The light emission device of claim 1, wherein the at least two LED diesinclude a blue LED die and a green LED die.
 23. The light emissiondevice of claim 22, wherein the phosphor material comprises aCaGa₂S₄:Eu²⁺ phosphor and a ZnGa₂S₄:Mn²⁺ phosphor.
 24. The lightemission device of claim 1, wherein the at least two LED dies include ared LED die and a blue LED die.
 25. The light emission device of claim24, wherein the phosphor material comprises a SrSCu+,Na phosphor and aCaSO₄:Bi phosphor.
 26. The light emission device of claim 1, wherein thephosphor material comprises a YAG material.
 27. The light emissiondevice of claim 1, wherein the at least two LED dies include anultraviolet LED die and a blue LED die.
 28. The light emission device ofclaim 27, wherein the phosphor material includes a CaMgSi₂O₆:Eu²⁺,Mn²⁺phosphor.
 29. The light emission device of claim 1, wherein the at leasttwo LED dies and phosphor material include a first LED die or phosphorhaving an aging profile including a degradation of light emission overits service life, and at least a second LED die or phosphor having anaging profile at least partially compensating said degradation of lightemission of said first LED or phosphor.
 30. The light emission device ofclaim 1, wherein the at least two LED dies includes dies differing fromone another in die size.
 31. The light emission device of claim 1,wherein the at least two LED dies and the phosphor material are in aunitary package, with the phosphor material including at least twophosphors in mixture with one another, wherein the phosphor material isdeposited over the at least two LED dies in the unitary package.
 32. Thelight emission device of claim 31, wherein the phosphor materialcomprises a glass or polymeric composition in which the at least twophosphors are dispersed.
 33. A method of generating light, comprisingexciting at least two LED dies having differing spectral output from oneanother, to emit spectral outputs from each of said dies, and impingingthe spectral output from at least one of said dies on phosphor materialincluding one or more phosphors, to responsively emit a phosphor outputas at least part of spectral output constituting said light.
 34. Themethod of claim 33, wherein said light is a white light.
 35. The methodof claim 33, wherein said light is other than white light.
 36. Themethod of claim 33, wherein the light substantially matches anillumination spectrum of sunlight, candle light, or incandescentfilament light.
 37. The method of claim 33, wherein the lightsubstantially matches an illumination spectrum of fire.
 38. The methodof claim 33, wherein the light is white light having a color temperaturein one of the following white light color temperature regimes (A), (B)and (C): (A) white light having a color temperature in a range of from1350° K to 1550° K; (B) white light having a color temperature in arange of from 2400° K to 3550° K; (C) white light having a colortemperature in a range of from 4950° K to 6050° K.
 39. The method ofclaim 38, wherein the white light comprises light having a colortemperature in white light color regime (A).
 40. The method of claim 38,wherein the white light comprises light having a color temperature inwhite light color regime (B).
 41. The method of claim 38, wherein thewhite light comprises light having a color temperature in white lightcolor regime (C).
 42. The method of claim 33, wherein the at least twoLED dies and phosphor material are disposed in a unitary package. 43.The method of claim 42, wherein the phosphor material overlies the atleast two LED dies.
 44. The method of claim 33, wherein the phosphormaterial is conformally coated on the LED dies.
 45. The method of claim33, wherein the phosphor material is coated on the LED dies, so that thespectral output of the LED dies traverses a substantially constantthickness of the phosphor material over the LED dies.
 46. The method ofclaim 33, wherein the phosphor material comprises a YAG material. 47.The light emission device of claim 1, wherein LED dies and phosphormaterial are matched in aging character thereof to provide apredetermined character of spectral output over life of the device. 48.The light emission device of claim 47, wherein said predeterminedcharacter of spectral output includes a transition in color of spectraloutput at a predetermined time during said life of the device.